Signal decoder



March 8, 1960 Filed Sept. 20, 1957 ClOC'K PULSE F/RS T PUA 5E SECOND PUL $5 FIRST PUC SE SECOND PUL SE COUNT 5 Sheets-Sheet 1 THU Inventor:

ROBERT C REA/ CK HAROLO J. MILLS By 355i? 5 Sheets-Sheet 2 HAROLD J N/LS By Waw Agent R. C. RENICK ET AL SIGNAL DECODER March 8, 1960 Filed Sept. 20, 1957 wwubo N s 9 kwmwk March 8, 1960 R. c. RENICK ET AL 2,928,045

SIGNALDECODER Filed Sept. 20, 1957 5 Sheets-Sheet 4 Inventor: ROBfkT C. RE'IV/C'K HAROLD J- M/LLQ' Agent United States Patfi SIGNAL nrzconnu Robert C. Renick, Plainiield, and l-I aro ldj. Mills,

N.J., assignors to International Telephone and Tele graph Corporation, Nutley, NJ., a corporation of Maryland 3 Application September 20, 1957, Serial No: 685,336 2"6 Claims. (Cl; 324- 68) This invention relates to a system for measjiringj the time spacingbetween signal pulses by counting clock pulses. I A V V Intelligence of one type or another may be sampled at set intervals and the sampled intelligence transmitted to a receiving terminal by various forms of pulse modulation,- such as pulse amplitude modulation, pulse width modulation, pulse code modulation, and pulse'tirne modulation. The arrangement ofthis invention is particularly unique to one form ofpulse time modulation wherein the time spacing between two pulses of a pair is varied proportionalto the sampled intelligence with at least the first pulse of I each pair beingvaried in'time. In this type'ofpulse time modulation, the time spacing between pulses of applse pair may be demodulated; or decoded by severaldiiferentmethods to recover the intelligence transmitted. One of the decoding methods accurately measures the time spacing; between the leading'edges oftwo pulses-of apulsepair by counting thenumber of locally generated clock pulses that occur between the-"leading edges of these two pulses: Previous decoders for this latter type of pulse time modulation have employed t-he'first pulse of the received pulse pair to start a counter which" counts the internally ge'nera'tedclock pulses whilethe second pulse of thereceived pulsepa'irstopped the counter: The value of the counts in the counter was ameasurerof the time spacing between the two" pulses of the pulse pair. Since bothpulses of ure received pulse pair-can occunin' randomtime'rel'ationwith respect to the timing-eithe internallygenerated clock pulses; it: is possible with the" prior art arrangement for aslight time shift'of less'thana full'clocle interval (the time interval betweeh adjacent clock pulses)" to appearas a double clockpulse change. In other words; the-resulting count of the clock-pulsesbetween-the pulses of a pulse pair woiild bein error by an extra counted" clock-pulse: t

Therefore; it is" an object of" this invention to provide" an improved "system-= for measuring the time spacing be tween signalpulses by counting clock'pulses;

Anotherobj'ect of this invention-is to reduce 'the error in'the resulting count producedbyasystem for measuring the time spacing between signal pulses by countingicloclc pulses? 1 Still anotheh object ofthis invention isitU'providea".

system" for measuring'the time s'pacing between-signal pulses" by counting "clock pulses resulting: iira count that''- has an error no greater than one counted clocle pulse?- Afeatii re of this iuvefition is the provision ot wnieaiis res onsive to the time-relation between-*a' fir'st of -1h signal pulses' and a time adjacent clock puls'e for delaying afollowing giial pulse by a't'leastone'of a number of p're' determine arfi'ounts and a -me'ans for countin g a *numbef of successive clock pulses between the time'pos'itmm of said first ofthe" sigiial pulses -ahd the first 'of th'e"delayed signal pulses.

' Another resent 'er-aiis inventioii -is"the pi'ovisiofi oi 2,928,045 P iatented Mar. 3, 1960 ,2 fer-imparting t e greatest time delay t'o a tollows gn ulse when th r stauran spacing exists beii a rst fifths gnal pulses and the first counted near pu d the smalls he delay to thefollowing signal pu se w ten the srria es iine spacing exists between the first of the signal pulses'and the first counted clock p'u v c v c Still another feature oi; this iuv ention is the provision of, aiae ans responsive to the clock pulses anda first of the signal puls s to determine the time position, of the first .5 I ii ilul purses in one of thecloclrpulse intervals a d to select at leas one of a number of predetermined tune delays in accordance with the determined time positioii of the, first of thesignal pulses for delaying a fol ing signalpulsethe selected amount; A counter provided to cour'1t tl'lt=. clock pulses betwccntthe first of thesig'nal pulses and the first ofthe delayed following signal pulses. v 1 i A further feature of this invention is theprovision of a plurality of normally non-conductive paths means to delay the second pulse of a pulse pair a plurality of different predetermined amounts, means coupling each of the delayed second pulses to predetermined ones of said paths, rneans to sequentially couple each of the cloclc pulses to each of said paths, and means to couple the first pulse of the pu lse pair simultaneously toisaid I paths, the-time coincidenceof the clock pulse and the first pulse of the pulse pair rendering at leastone of said paths conductive to pass at least one of the delayed secondpulses to the output of the conductive path; A clock pulse counter isiemployed to count the clock pulses betw ecn the firs t pulseof the pulse pair and the ou ut pulse of fthe conductive, paths; .7 .i

ne above-nientioned and other objects and features of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which; t

l F;ig l is a timing 'diagram illustrating the error present in decoding-systems of the prior art;

Big-,2 is aschematic; diagramjn block form ofan em- 3, 4, and S a're timirigdiag-ra'ms useful" in explaining the operation of the system ofFig; 2for three different time positions ofit'ne pulsesof apulse' pair.

Referring to Fig: 1, a timing diagram'isiillustrated to fur ier point-j out in pictorial form the counting error that is presentiin the prior arfa'rrahgementsfor measuring the time spacing between a pair of signal pulses by countiri'g; clockgpulses-,therebetween. Curve A illustrates the clock" pulses that are generated internally of a receiving station or terminal having-a definite repetitionfr equency and hence a timing interval, T, therebetween. To" accurately measure the time spacing between a first and secondreceived pulse, such as the pulses ofa pulse'pa'ir, it-isneces'saryfOr the counter to count'the' clock'pulses occurring between the two received pulses; Curve Bl illu'strates' the tiine position of '3" first received pulse with respect to a'c'l'ock' pulse of curve A. Curve C illustrates the second received pulse in a'particular time relatio'nsh'ip tothe first received" pulse and another of the clock pulses of curve A: A' counter for" counting theclock pulses of curveiA is started by the first received pulse, the pulse of curve B; a'nd would thenbe stopped by the occurrence of and F,*Fig; l'iand-ican assum the illustratedrelationship wit-lithe' clock pulses Ofcur-ve A. I The time shiftof these I two' pulses-is"'much*less than the time'intervaYTof'the clock pul seswf current The same process of startingand stopping a counting operation results in a count of seven as depicted in curve G. Obviously, for a change considerably less than T, there should not be a change in the count by two. It is obvious, therefore, that the count depicted in curve G is in error by an extra clock pulse and hence would give the wrong measure of time spacing between the two signal pulses and, in turn, the intelligence would not be properly decoded or demodulated.

It has been found that the counting error as depicted in Fig. 1 can be reduced an appreciable amount by employing the system described herein, an embodiment of which is illustrated in Fig. 2. The system is so arranged that the closest clock pulse to the received pulses is, in effect, included in the count and thereby reduces the counting error present in the prior art arrangement. The improved system for measuring the time spacing between signal pulses by counting clock pulses includes a clock pulse source 1 and a source of signal pulses 2 which may be a terminal receiver having means therein to separate a first received pulse for transmission over conductor 3 and a second received pulse for transmission over conductor 4. The system further broadly includes means responsive to the time relation between a first of the signal pulses and a time adjacent clock pulse for delaying a signal pulse at least one of a number of predetermined amounts, generally identified in Fig. 2 by reference character 5, and a means for counting a number of successive clock pulses determined by the time position of the first signal pulse and the first of the delayed signal pulses, indicated generally by counter 6. Means 5 includes a delay line 7 having a plurality of output taps therealong to delay a clock pulse for occurrence in subdivislons of the time interval between adjacent clock pulses. The embodiment of Fig. 2 used for the purposes of explanation illustrates that the clock pulse time interval is subdivided into four parts. It is to be'understood, however, that the clock pulse time interval could be divided into any desired number of subdivisions with the increase in subdivisions reducing the error of the measuring system.

The output of the delay line taps 7a to 7d are coupled to normally non-conductive paths 8, 9, 10, and 11 in a manner whereby path 8 receives a clock pulse of source 1 which experiences no delay time, conductive path 9 receives a clock pulse having a time delay of T/ 4, path 10 receives a clock pulse having a time delay of T/ 2, and conductive path 11 receives a clock pulse having a time delay of 3T/4. Each of the normally nonsection 27 has a delay equal to 3T/4, while the remaining delay sections of delay line 26 have a time delay equal to T/4, the same delay experienced by the clock pulse to occur in the subdivisions of the time interval T. The greatest delayed second pulse, the output of tap 28, is coupled by means of conductor 29 to AND circuit 16 of normally non-conductive path 8. The least delayed second pulse, the output of tap 30, is coupled by means of conductor 31 to the AND circuit 19 of non-conductive path 11. The output of tap 32, the next largest delay for the second received pulse, is coupled to AND circuit 17 of normally non-conductive path 9 and the output of tap 33, the next largest for the second received pulse, is coupled to AND circuit 18 of normally nonconductive path 10. It will be observed that non-conductive path 8 has coupled thereto the clock pulses experiencing the smallest time delay and the second received pulse experiencing the largest time delay and non-conductive path 11 has coupled thereto the clock pulse experiencing the largest time delay and the second received pulse experiencing the smallest time delay. The inter mediate normally non-conductive paths receive delay clock pulses in sequentially increasing order of delay 8 to 11 of the delayed clock and second received pulses conductive paths 8 to 11 includes as components thereof a coincidence device indicated respectively as logical AND circuits 12, 13, 14, 15, a coincidence device illustrated to be logical AND circuits 1'6, 17, 18, and 19, respectively, interconnected by bistable devices 20, 21, 22, and 23, respectively. Bistable devices 0 to 23 may be bistable devices, such as Eccles-Jordan type multivibrators.

The output of normally non-conductive paths 8 to 11 are coupled in common to a logical OR circuit 24 which will pass the output of either or all of the normally non-conductive paths 8. to 11 if there is an output from these paths. The out-put of the OR circuit 24 is coupled to a blocking oscillator 25 to provide a reshaped pulse for utilization in counter 6.

As illustrtaed in Fig. 2,-the first received pulse of source 2 is coupled over conductor 3 for simultaneous application to the AND circuits 12 to 15, respectively, of normally non-conductive paths 8 to 11. Delay line 7. sequentially applies a clock pulse of source 1 to the AND circuits 12, 13, 14, and 15, respectively, of normally non-conductive paths 8, 9, 10, and 11.

The second received pulse output of source 2 is coupled by means of conductor 4 to delay line 26 which includes therealong a plurality of delay taps spaced by predetermined different delay times to provide predetermined different delays for the second received pulse.

As depicted in the illustration of Fig.. 2, the first delay.

that make it possible to shift the second received pulse in time a selected amount to assure that sufficient clock pulses are included in the count to account for the pre ceding clock pulse when the first received pulse occurs in the first half of the clock pulse time interval and the following clock pulse when the second received pulse occurs in the last half of the clock pulse time interval.

The first received pulse output of source '2 is also coupled by means of conductor 34 to a bistable device 35 disposed in counter 6. The operation of the first pulse coupled over conductor 34 to bistable device 35 is to trigger the bistable device into one condition of stability which produces an output therefrom. This output is coupled to AND circuit' 36 which readies AND circuit 36 topass the pulses coupled from clock pulse source i by means of conductor 37. Thus, the clock pulses on conductor 37 are passed through AND circuit 36 to any known chain of bistable counters 38, the conduction condition of each counter indicating the number of pulses which have been applied thereto. The counting operation will commence when the first received pulse is applied to bistable device 35 and will continue until/there is an output delivered from blocking oscillator 25 to bistable device 35 to trigger this device into its other stable condition which produces no output. This operation or triggering of device 35 to its no output condition will cause the AND circuit 36 to block the clock pulses and hence stop the counting of counters 38. The number of clock pulses that have occurred between the first received pulse and a delayed second received pulse will then be indicated on counters 38. It is then merely neca sesgeee structural organization oft-the: system -forkmeasuring;the tii'ne spacing between signal""pulses::lty counting clock pulseszwhich will reduce: theerron off the count previously obt-ainwlin thez-prior arrangements. To: fa'c-ilitat'e'the understanding of? this. invention, three timing: conditions of: the pulses of the'pulseipairsi arew showniini. the timing diagram of Figs: 3 4; and1152 and: will: be discussed in connection. with the operationi'of; the systenrofiFigzl;

Referring to; Figs; 2t and 3;; its will; be 'observed that the output. ofisourcei 1; ast represented: by" curve A, has alparticulan timetintewal between adjacentcloclepul'ses indicated; as: T. It is proposed in; thissystern. that this clock interval be subdivided into: subdivisions? of 3.13116- determin'ed nunihetz. ,pointedrout hereinabove for purposes of. illustration",- thertirneiintervall. between adjacenticlo'cle puiseshas been; divided into four'suhdivisions with the understanding; thahthexclock; pulse interval; can be divided: intoi more' than foun subdivisions with 2 iri+ creasing..reduction in the counting: error; lttwill'iberfurr then observedithet the width ofithe: cloclcpulse: isxape proximately ret nal.- to; the; time of a subdivision;v hence; a subdivision is onequartert T; and thewwidth'fof a clock pulseris alsoi approximatelyr one-quarter 'TI Before continuin'g with tli'e operation: of the: circuitofiFi'g: 2;.itrwill be observed that the first received pulse"illustrated in curve E: and: the" second. received: pulse illustrated" in more accurate measurementzof the time: spacingv between 'therpulses i offatpulse pair:- Thus; to bexmorexaccurate due to. closenesswotfi t'netsecondi received-pulsetoclock pulse 42zz; the system should. count; on r: clock pulses. 'This,1in' itself; wilhintroduee: a slight: error: but is: oft-:eourse less than the: error introducedifitliisc closestt'cloclt pulse isi no't read: Hence, if: a si'gnallpulse occursr between OandT/Z} it is desiite'di that: the preceding cloclczpulse be-read. If; however; the signal pulse; OCCUI'SE' between T/Z andT,'it is desirable that'therfollowing clhclepulse be counted which gives, azmorez accurate indication of the? time spacinglbetweentthe pulsesoi a: pulse pair.v

The output-of" source 1', the' clock pulses, are coupled directly to'AND; circuit '12 bydelaylinetap "7a; the output of delay line tap i7b,.curvevB,xFig-. 3',lis-coupled-zto the AND circuit 15,;the output' of: delay tap 7c: is coupledito AND circuit 14' having attime; displacement illustrated in curve C, andtheoutput of delay line tap 7d having a displacement as; illustrated in: curve: D is the sequential applicationv of" a; clooli pulse to normally nonconductive paths=8',-:9-;1'0; andlli through the means coupled to AND circuit 15: This arrangement-of'delay' line 7 and the coupling of' the; taps; theretoprovided for 4 -to delay line: 2 6. This sec 'endirfceived pulseis indi H cat'ed in curve J, Fig; 3- The: delay line: 2'6 produces;

respectively, at taps 30, 32, 33 ,an'd 28 the delayed sec ond pul s'es 'having a predeterlninned amount of delay. These delayed s'e'cond pulse output's frorn delay-"lihe'ttaps 30, 32, 33 and: 28 are: fixedlyooupled to: AND circuits 19; 18} 17:, and 1 6} respectively," tlrereby apply ing the second received ulse with the lowest delay: to: AND circuit 19 and: the second ulsewith: tire; highest delay to- A NDcircuit 16 with the intennediate -ANm circuits 17 and 18 having applied thereto the" second pul se of diiferent'time delays of intermed-iate and successive re lati'on'sliip withthe delayed si'gnalsrapplie'd to AND cir cults-16mm 1 9; This prearranged conntectidh cif tlie out put taps of delayline 26 to the-appropriate?andlselectetl AND circuitsof normally" non-commetivepathsi 8;. 9'5 1'0; and Zl-l eifectively;has the -following function; T-liesec and received pulse delayed the: least aniou'n't coupled from delay line tap 38 looks at circuit -l9 and s'ees tha'tthe AND circuit is-blockedn'o it anditlierefoieg'no output results. This is illustrated in curve R', 31 "Elie-nextlargest delayed seeond:receivedulse': at the outputof delay-' line ta'p' looks at 1 AND circuit 1 8 again" findsthisnormally'nOnwQnduCtive path 1 component ltl b'locked t'o it and; hence, no output can be derive'd from 18; This is illustrated: in curve Q; Fig; 3 The next largesti delayed second received" pulse co'uple'd from ,out'put tap 33 looks at AND circuit L7" in normallynenconductive path 9 and finds-this AND c'ii'cuittblocked preventing its-passage to' th'e output which is illustrated il't curve P; Fig 3. However when -thei nexelargest de layedsecond received pulse at the: output of 281 isicou pled to-AND circuit 16'; it is found thttlAND' circHitlfi is open and can pass to the 'output thereofi This is illi1s trated-in curve O; Eg -3t The output ot AND circuit 1'6i'is coupled to: the 0R circuit 24 which: passes tezeiis output the pulse indicated in curveS, Fig. 3p This pulse output triggers blocking oscillator 25 to produce a puis'e as indicated in curved, Fig; 3. As pointed outiherein= above, thefirst received pulseis'conductedover line 34 to'trigger bistable device 35: into a stable condition pro ducing an output pulse'4l, curve U, 3 ltiwill lie notedthat time coincidence: is present betwe'en theflead iiig edge of p'ulse 41 and the leading edge--'of the first received pulse, 'curve B, Fig 3 The triggeringi of'bistable device 35; to its output condition' opens the AND circuit 36 to permitthe clock pulses: coupled oileri 37 to appear at the;output'ofcircuit 36 forscountingzthereoh J the count being illustrated in curve V, Fig. 35: Devic'e 35 is-r'etu'rned to its? no output condition: by the application the output of blocking oscillator'25f as: illustrated by thetirne coincidence-oi the leading edgexofiltheroutput in ANDcircuit 12 and of coursewillvopen the AND circuit 1'2 to" allow an: output therefrom." for triggering bistable'devicejfiifromi its condition of noloutput to:its'

stablcondition' ofloutput as indicated by pulse 4!); curve F, Fig-3. Since' the' first' reeeived pulseiwasi noteoincident" with 'any of" the -other-suhdivision or Vernier The second received pulse is coupled over conductor of ourv'e'T-g Fig: 3 and the trailing ed'gexofi pulse 41, curve U, Fig; 3. Tliisfapplication:of:the outputaofaos cillator 25 s-tops-the eounting process inxcounte1 38 and renders a count of five as depicted in curve"V', Fig.1- 3; If thecount' of the original first received-aud second' rec'eived pulseof curves; E; and I are comp'ared withi re spec-t to the output ofsourcel; curveA, Fig. 3, itlwill be observed that the count should-have been fourandtnot resulted: in: the; maximumtime delay tothe: following or second? receivedpulses- Thiswassures; that ithefsecond received pulse'z-has sufficientxdelaw tozassur'e thattthat numberrof: pulses: are counted-:to make upifor the tproxw The illustration in' this" timing diagram. of; Fig. 3

This spacing: between the l imity of the first received pulse to a preceding clock pulse, which under the conditions specifiedabove, assures that this clock pulse is read.

It will further be noted that the first delay section of delay line 26 has a delay equal to 3/ 4T, while the remaining delay sections have a time delay equal to the time of the subdivisions, in other words, T/4. This 3/4 time delay is important and is the minimum time delay that the second received pulse should experience. This follows from the fact that if the first pulse is just in the fourth subdivision of a clock pulse time interval and it is desired that the clock pulse of the next interval be read, this gives a delay of T/4 that should be imparted to the second pulse. Now, if the second pulse is just within the third subdivision of a time interval, it is desirable that the following clock pulse be read to give an accurate measure of the time spacing since the second pulse is closer to the following clock pulse than the preceding one. This would therefore resultin a delay of T /2 to assure that the following clock pulse is read. Therefore, to assure the proper count in accordance with the principles of this invention, the minimum time delay that can be experienced by the following signal pulse is 3T/ 4 due to the time relation between the first pulse in the fourth subdivision of a time interval and a second pulse being located just in the third subdivision of a time interval. This minimum delay is necessary regardless of the number of subdivisions as long as it is desired to read to the closest clock pulse in relationship to the signal pulses. If the subdivisions are increased, the first or minimum delay of line 26 should be 3/ 4T, and the other delay sections would be equal to the time of a subdivision. The maximum delay will increase as the clock pulse time interval is subdivided into smaller and smaller increments. This is illustrated by the following examples. Assume that the clock pulse time interval is divided into eight subdivisions. The delay necessary for delay line '7 would be 3/4T+seven l/ 8T delay sections, resulting in a total time delay or maximum time delay of 13/ ST. If it is desired to subdivide the clock pulse time interval by sixteen subdivisions, it will be recognized that the minimum time delay or first section will have a delay of 3/4T, while the remain relay sections will have a time delay of l/ 16 per section, resulting in a maximum time delay of 27/161. If the subdivision of a time interval between adjacent clock pulses is carried to smaller and smaller increments, it will be recognized that the maximum time delay experienced by the second received pulse approaches a delay of 2T.

Referring to Fig. 4, there is illustrated therein another condition of different time spacing of the first and second received pulses. It will be observed that the first pulse, curve B, Fig. 4, occurs in the fourth subdivision of the time interval T and that the second received pulse straddles the third and fourth subdivision of the clock pulse time interval; Due to the time spacing, the correct count of the circuit of the system of this invention should be three since the second received pulse is closer to clock pulse 43 than it is to clock pulse 44, and the first received pulse occurs prior to the clock pulse 45. As described in connection with Fig. 3, the output of clock pulse source 1, curve A, Fig. 4, sequentially samples the normally non-conductive paths 8, 9, 10, and 11 through the medium of AND circuits 12, 13, 14, and 15, while the first received pulse is coupled over conductor 3 simultaneously to AND circuits 12, 13, 14, and 15. Since the subdivision or vernier clock .pulses 46, 47 and 48 are not time coincident with the first received pulse of curve E, Fig. 4, AND circuits 12, 13, 14 will maintain paths 3, 9, and in the non-conductive state. However, time coincidence occurs between the vernier pulse 49 and the first received pulse of curve B, Fig. 4. This means that bistable devices 20, 21, 22 remain in their stable condition of no output, while bistable device 23 will be flipped from its stable condition of no output to its stable condition of output as indicated by the pulse 50 of curve I, Fig, 4. The output of bistable device 23 now readies or conditions AND circuit 19 for passage of the predetermined delayed second pulse which is the output of delay line tap 30 as depicted in curves K and R, Fig. 4. The output of AND circuit 19 produces an output from OR circuit 24 which triggers the blocking oscillator 25 to stop the counting process in counter 6 which was started by the first received pulse as indicated in curve U, Fig. 4. The resulting count of counter 6 is three, the correct count as indicated above. It will be observed from reviewing Figs. 3 and 4 that the time position of the second received pulse has no effect whatsoever upon the delay imparted thereto. The first received pulse is the controlling pulse in this system and is such that the time relationship between the first received pulse and a time adjacent clock pulse determines the predetermined delay that is imparted to the following or second pulse. The normally non-conductive paths 8, 9, 10, and 11 act as channeling means for the differently delayed second received pulse such that the properly delayed second received pulse is passed to the output to stop the counting of counter 6 and hence produce a more accurate count or measure of the time spacing between the first and second received pulses.

The timing diagram of Fig. 5 illustrates that the first received pulse straddles two subdivisions, namely, the second and third subdivisions of the clock pulse interval. The following discussion will illustrate how the system of Fig. 2 operates under these conditions. As the clock pulses of source 1 simultaneously sample the presence of the first received pulse in AND circuits 12, 13, 14, and 15, it is found that coincidence occurs between the first received pulse and vernier pulses 51 and 52 thereby producing output from bistable devices 21 and 22 which conditions AND circuits 17 and 18 for passage of the outputs of delay line taps 32 and 33 of delay line 26. Hence, as illustrated in curves P and Q, Fig. 5, we have outputs from AND circuits 17 and 18 with the output from AND circuit 18 preceding in time the output from the AND circuit 17. These outputs are the only outputs from the normally non-conductive paths 8, 9, 10, and 11 and are coupled to OR circuit 24 wherein an output pulse 53 is produced which has a width corresponding to the width of both the outputs from AND circuits 17 and 18. The leading edge of the output of OR circuit 24 triggers the blocking oscillator 25 and hence the leading edge of the output of oscillator 25 stops the counting process are only two clock pulses between the first received pulse and the second received pulse, we get a count of three 'since the first received pulse is closer to clock pulse 54 than it is to clock pulse 55 and, hence, we derive a more accurate measure of the time spacing between the two received first and second pulses.

Referring again to Fig. 2, it will be observed that the output of source 2, labeled second received pulse, is coupled to a delay line 56, the output of which is coupled to a reset pulse shaper 57 and a reset pulse shaper 58. The output of these repulse shapers is coupled respectively to bistable devices 20 to 23 and bistable counters 38 to assume that the bistable devices are in their proper starting condition, hence, in the stable condition of no output after the cycle of measuring the time spacing between two signal pulses is completed to ready these circuits for measuring the time spacing between the next two signal pulses.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims.

cesarean 11.v A system; for; measuring the. time; spacing: between signal .pulsessby; counting clock pulseszcomprisinga, source of clock-pulses, a.so.urce of; signalpulses; meanscoupled to. Said. source of clioclc pulses. and said source of signal pulses responsive. to the; timevrclation. betweemai first: ofsaid signal pulses and. a time, adjacent cloc. pulselfcr delaying; a; second signal. pulse following saidrfirst: signal pulse. by at least one of a number: OfLprcdetermined amounts-andimeans coupled to said;source-Qfi cloaklpulses: for, counting: a: number. of successive; clock pulses. deter-- mined by the. time position'of said firstpulse-andahefirst: of said. delayed second signal pulses. 2;. A systemfor. measuring thejtime. spacing between signal pulses by counting clock; pulses.comprising a: source of clock pulses, a source: of signal; pulses, means coupled; to: said; sourcelxoi' clock. pulses.- andlrsaidsource of signal pulses responsive.=;to: thetime; relation between a: first ofisaid. signal pulsesand-.5 a; time adj scent clock pulse for deiayingi a. second; signal. pulse; following: said first; signal; pulse.- by at least: one: of; anumbeuofpred'ea termi'ned. amounts, and. means; coupled. to said; source; of clock:- pulses and responsive to. Said'firstofr saidr'signal pulses: and the: first of said. delayed. signal: pulses for counting the clock pulses between, said first. signal pulse and tliefirst of said delayed secondsignalpulses...

3. A system, for measuring the, time spacing-between signal; pulses by counting clock pulses; comprising in source of clock pulses, a sourcepof signal; pulses, means coupled to said source'ofclock' pulses and said source. of

signal pulses; responsiye; tQrt'he: timexrelation between a first of said; signal: PlllSfiSL-H1ldjt a; time adjacent clock. pulse for delaying: as second; signal: pulse. following said first signal pulse by one of anurnben. of predeterminedamounts, and;.-'means coupledzto; saidisourceeot clock Pulses for: counting; a; number ofiafsuccessive :clockixpulses determined: by, the. time: position; of; said; firstizsignah pulse andsaidi delayed; second-signal pulse...

4; A: system; fonmeasuring: the timespacing between sign-at pulses by; counting; clock; pulsescorn'prising: a source; of clock. pulscs;,.a:sour.ce of'signalpulses; means coupled .to saidisource' of. clock: pulses andisaidisourceiof signal? pulses. responsive'to, the; i time relation "between? a first? of said. signal pulses: and. a: time: adjacenn .cloclsipulse for delaying at second. signal pulse following said: first signal pulse. by; oneaof'. a. number of; predetermined of a number"of:prcdeterrnineda amounts, andrmeans: cou.-- plcdi to-said;source of clock PIlISESEfOIFCOllBYlHg; anurnben A. system. for; measuring the timev spacing: betweciii signal; pulses: counting clock pulses: comprising; .a sourcesoficlockv pulses, a source of signal pulses,:means. coupledio, saidasource. of. clock pulses and, said source of signal. pulses. responsive. to the time relation between a filSIOfiSfi-itl signalpulses and. a time adjacent cloclepulse; for delaying a. second signal pulse. following saidrfirst signal; pulse by a number of predetermined different time. delays, the greatest of said time delays being associated with. the greatest spacing between said first. of said signal pulses and the first counted clock pulse, and: means coupledttozsaid.v source of clock pulses and responsive. to; said first v of'saidz. signal; pulses and said delayed'second signal. pulse for counting the clock pulses. between said first signal pulse and said delayed second signal pulse.-

8; A system for: measuring the time spacing between signalpulsesby countingv clock pnlsescomprising a source 7 of; clock pulses, a sourcenof signal pulses, means coupled to saidssource of clock: pulses and said. source of signal pulses: responsive. to; the. time relation between. a first of. said. signal pulses and a time adjacent clock pulse for delaying a second signal. pulsefoll'owing said first: signal 7 pulseibya number'of'predetermined different time delays, thegreatestof: said time delays being associatedwith theugreatestcspacing between said first of said signal pulses and: the first counted clock pulse andthe smallest of said time delays being associated with the smallest spacing. between said first of. said signal pulses and the first counted clock' pulse, and means coupled to saidj.. source of. cloclc pulses and. responsive to said first of said.

' signal pulse byatleast a selected-one. of a number of predetermined. ditferent time delays, the greatest: of said time delays being associated with the greatest spacing, between. said first of said signal pulses and thefirst counted clock pulse, and: means: coupled to said: source of clock pulses and responsive to said fi'r-suofsaid? signal I pulses and the'first ofsaid delayed second signalpulses of successive clock pulses. determined; bythe: time position of: saidfirst signal pulsetand the next adjacent sone'of said delayed signal pulses:-

6.: A. system for measuring;- the: time-spacing between signal pulses by counting. clock pulses: comprising 'a source of clock pulses; awsource. of sequential: signal pulses, means. coupled'itoisaid source ofclock; pulseszami said source: of signal pulses responsiveito the time; res lationzhetween afirst of saidlsignalt pulses-ands'a 'tiine adjacent clock pulse for delaying the, next adjacent signal pulse by one of, a number: of predetermined amounts, and? means coupled to said source. of clo'ck pulses: and responsive to'said first; of said signalpulseseandv said dc layed signal pulse for counting the clock pulses 1 between said first-*signali pulseandr'said'delayed' signahpulse:

for connting the; clock: pulses. between said first: signal pulses: andthefirst of said: delayed second signalpulse's: A 1system-.-for measuring the time spacing between signal. pulses byrcounting clockzpulses comprising asource of clock pulses,aa source of signal. pulses, means coupled to; said source of. clock pulses and said source of signal.

pulses responsive to the. time relation between a first as j said signal pulsesuand a time adjacent clock pulse for delaying a second signal pulse following said first signal? pnlseby at least a selected one of a numberzofipredeterminedxdifferent time delays, the greatest of said'time delays being associated with the greatest spacing between. saidfirst: of said signa-lgpulses and the first counted clock pulse and the smallest of said time delays being associ atedwith the smallest spacing between said first of said signal pulses. and the first counted clock pulse, and meansecoupled-to. said source of clock pulses-and responsiveto said first of said signal pulses and the'first ofisaiddelayed second signal pulses for counting theclock.

pulses. between said first signal pulse and the first ofsa-id said time intervals and to select at least one of a number of predetermined time delays in accordance with the determined time position in said time interval for delaying a following signal pulse said selected amount and means coupled to said source of clock pulses and responsive to said first of said signal pulses and the first of the delayed signal pulses for counting the clock pulses between said first of said signal pulses and the first of said delayed signal pulses.

12. A system for measuring the time spacing between signal pulses by counting clock pulses comprising a source of cloclc pulses having a given time interval therebetween, means responsive to said clock pulses to provide Vernier timed for occurrence in each of a plurality of subdivisions of said time interval, a source of sequential signal pulses, means responsive to a first of said signal pulses and at least one of said Vernier pulses to determine the subdivision in which said first of said signal pulses occurs and to select at least one of a number of predetermined time delays in accordance with the determined subdivision for delaying a following signal pulse said selected amount, and means coupled to said source of clock pulses and responsive to said first of said signal pulses and the first of said delayed signal pulses for counting the clock pulses between said first of said signal pulses and the first of said delayed signal pulses.

13. A system for measuring the time spacing between pulses of pulse pairs by counting clock pulses comprising afsou'rce of clock pulses, a source of pulse pairs, means coupled to said source of clock pulses and said source of signal pulses responsive to the time relation between the first pulse of said pulse pairs and a time adjacent clock pulse for delaying the second pulse of said pulse pairs by at least one of a number of predetermined amounts, and means coupled to said source of clock pulses and responsive to said first pulse and the first of said delayed second pulses for counting the clock pulses between said first pulse and the first of said delayed second pulses.

14. A system for measuring the time spacing between the pulses of pulse pairs by counting clock pulses comprising a source of clock pulses having a given time interval therebetween, a source of pulse pairs, means coupled to said source of pulse pairs responsive to said clock pulses and the first pulse of said pulse pairs to determine the time position of said first pulse in one of said time intervals and to select at least one of a number of predetermined time delays in accordance with the determined time position in said time interval for delayng the second pulse of said pulse pairsaid selected amount, and means coupled to said source of clock pulses and responsive to said first pulse and the first of said delayed second pulses for counting the clock pulses between said first pulse and the first of said delayed second pulses.

. 15. A system for measuring the time spacing between the pulses of pulse pairs by counting clock pulses comprising a source of clock pulses having a given time interval therebetween, a source of pulse pairs, the timing of said pulse pairs being in a random relationship with respect to the timing of said clock pulses, means coupled to said source of pulse pairs responsive to said clock pulses and the first pulse of said pulse pair to determine the time position of said first pulse in one of said time intervals and to select at least one of a number of predetermined time delays in accordance with the determined time position in said time interval for delaying the second pulse of said pulse pair said selected amount, and means coupled to said source of clock pulses and responsive to said first pulse and the first of said delayed second pulses for counting the clock pulses between said first pulse and the first of said delayed second pulses.

r 16. A system for measuring the time spacing between the -:pulses of pulse pairs by counting clock pulses comprising a source of clock pulses having a given time interval therebetween, means responsive to said clock pulses to provide vernier pulses timed for occurrence in each of a plurality of subdivisions of said time interval, a source of pulse pairs, means responsive to the first pulse of said pulse pairs and at least one of said Vernier pulses to determine the subdivision in which said first pulse occurs and to select at least one of a number of predetermined time delays in accordance with the determined subdivision for delaying the second pulse of said pulse pairs said selected amount, and means coupled to said source of clock pulses and responsive to said first pulse and the first of said delayed second pulses for counting the clock pulses between said first pulse and the first of said delayed second pulses.

17. A system for measuring the time spacing between the pulses of pulse pairs by counting clock pulses comprising a source of clock pulses having a given time interval therebetween, means responsive to said clock pulses to provide Vernier pulses timed for occurence in each of a plurality of subdivisions of said time interval, a source of pulse pairs, the timing of said pulse pairs being in a random relationship with respect to the timing of said clock pulses, means responsive to the first pulse of said pulse pairs and at least one of said vemier pulses to determine the subdivision in which said first pulse occurs and to select at least one of a number of predetermined time delays in accordance with the determined subdivision for delaying the second pulse of said pulse pairs said selected amount, and means coupled to said source of clock pulses and responsive to said first pulse and the first of said delayed second pulses for counting the clock pulses between said first pulse and the first of said delayed second pulses.

'18. A system for measuring the time spacing between the pulses of pulse pairs by counting clock pulses comprising a source of clock pulses, a source of pulse pairs, channeling means having a plurality of normally nonconductive paths therethrough, means coupled to said source of pulse pairs to delay the second pulse of said pulse pairs a plurality of different predetermined amounts, means coupled to the last mentioned means to couple each of the delayed second pulses to predetermined ones of said paths, means coupled to said source of clock pulses to sequentially couple each of said clock pulses to each of said paths, means coupled to said source of pulse pairs to couple the first pulse of said pulse pairs simultaneously to said paths, the time coincidence of said clock pulse and said first pulse rendering at least one of said paths conductive to thereby pass at least a given one of said delayed second pulses to the output of said channeling means and means coupled to said source of clock pulses and responsive to said first pulse and the first output pulse of said channeling means for counting the clock pulses between said first pulse and the first output pulse of said channeling means.

19. A system for measuring the time spacing between the pulses of a pulse pair by counting clock pulses com prising a source of clock pulses, a source of pulse pairs, channeling means including a plurality of normally nonconductive paths, an input for each of said paths and a common output for each of said paths, means coupled to said source of pulse pairs responsive to the second pulse of said pulse pairs to provide a plurality of pulses at the output thereof each delayed a ditlerent amount with respect to the time position of said second pulse, means coupled to the last mentioned means to couple each of the delayed output pulses therefrom to the input of a dilferent one of said paths, said delayed output pulse having the largest amount of delay being coupled to the first of said paths and said delayed output pulse having the smallest amount of delay being coupled to the last of said paths, means coupled to said source of clock pulses to sequentially couple each of said clock pulses to each of said paths from said first of said paths 13 to said last of said paths, means coupled to said source of pulse pairs to couple the first pulse of said pulse pairs simultaneously to said paths, the time coincidence of said clock pulse and said first pulse rendering at least one of said paths conductive to thereby pass at least one of said delayed output pulses to the common output of said paths, and means coupled to said source of clock pulses and responsive to said first pulse and the first of the delayed output pulses at said common output for counting the clock pulses between said first pulse and said first of the delayed output pulses.

20. A system for measuring the time spacing between the pulses of a pulse pair by counting clock pulses comprising a source of clock pulses, a source of pulse pairs, a plurality of signal channels each including a first coincidence device, a second coincidence device and a bistable device normally in the condition of no output coupled between said first and second coincidence devices, a first delay line coupled to said source of pulse pairs responsive to the second pulse of said pulse pairs, said first delay line having a plurality of output taps spaced therealong to provide a plurality of output pulses each having a dilferent predetermined time delay with a respect to the time position of said second pulse, the

14 taps of said first delay line being coupled to the first of said channels, a second delay line coupled to said source of clock pulses, said second delay line having a time delay equal to the time interval between adjacent clock pulses and a plurality of output taps therealong having an equal time spacing therebetween to delay each of said clock pulses for occurrence in a different subdivision of said time interval, means coupling each of the output taps of said second delay line in successive order of pulse delays to said first coincidence device of successive ones of said channels, the first of the output taps of said second delay line being coupled to the first of said channels, means coupled to said source of pulse pairs to couple the first pulse of said pulse pairs simultaneously to each of said first coincident devices of said channels, the time coincidence of said first pulse and said delayed clock pulses in said first coincident device of at least one of said channels rendering said first coincident devices conductive, the conduction of said first coincident device triggering said bistable device coupled thereto to its condition of output to condition said second coincidence device coupled thereto to pass the delayed output pulses of said first delay line coupled to said conditioned second coincidence device to the output of said channels and means coupled to said source of clock pulses and responsive to said first pulse and the output pulse of said channels for counting the clock pulses between said first pulse and the output pulse of said channels.

No references cited. 

